Take a straw poll of 100 people in the street and ask them if they’d like to be ‘greener’, or lead a ‘greener’ lifestyle. I am sure that very few of them would say no. Being green to most people means improving sustainability, helping the environment and reducing harmful emissions and unnecessary waste.

Many corporations are also striving to be more green: the supermarkets, high street names, manufacturing industries, and the energy industry. But what exactly does ‘green’ energy mean? Is it different from renewable energy? And how green is green?
Most people take the definition of renewable as coming from resources that are naturally replenished such as wind, hydro-power (water) solar power, geothermal and biomass. About 16% of global energy currently comes from renewable sources (10% of this is biomass, 3% hydro-electric and the remaining 3% from wind and solar (see diagram below)).
Despite the ‘renewable’ tag, there are pros and cons with each of these sources of power, not least that renewables alone do not generate enough fuel to meet our current or future needs.

Wind power for example is generally seen as a very clean source of power, but what damage is done to the environment in building the wind turbines? You need a lot of wind turbines to supply relatively little power. Many are located off-shore (in fact the UK is the biggest producer of off-shore wind-powered energy), but many are not. Some would, and do, say that covering our countryside with wind turbines is definitely not green. They require a lot of heavy-duty materials to build, and what happens if the wind doesn’t blow for a couple of days? You have a lot of capacity that is standing unused, so they cannot be relied upon as a primary energy supply. Does the energy they generate create enough of a justification for the fact that they can be a blot on an otherwise unblemished landscape.

Let’s take hydropower as another example. Once a hydroelectric complex is constructed, the project produces no direct waste, and has a considerably lower output level of the greenhouse gas carbon dioxide (CO2) than fossil fuel powered energy plants. The cost of hydroelectricity is relatively low, making it a competitive source of renewable electricity. It is also a flexible source of electricity since plants can be ramped up and down very quickly to adapt to changing energy demands. However, damming interrupts the flow of rivers and can harm local ecosystems, and building large dams and reservoirs often involves displacing people and wildlife. And some environmentalists complain about the number of fish and other river/sea creatures that have become stuck in them and lost their lives. Furthermore; how many more realistic damming sites are there in a developed country such as the UK?

Solar power probably has the minimum environmental impact, but is patchy, and can only generate a relatively small amount of power, usually on a domestic scale. It is currently expensive to install and is a massive capital investment to make in your home: you’ve got to be pretty sure you will live there for a long time to make it a worthwhile exercise. Industrial sized solar power plants are simply uneconomic under current production technologies when compared to both fossil fuel and other cheaper renewable alternatives.

Biomass is currently the most abundant of the renewable fuels. It does however involve burning large quantities of organic materials, mostly wood, to produce energy. This is okay if new trees are planted at the same rate, but could end up being unsustainable and more damaging than fossil if the replanting rate is insufficient. This is an industry prone to fraud given the logging operations in the third world. Other sources of biomass fuel include plant or animal matter, food waste or algae. Some of these produce methane gas which is then burned, which contributes to C02 emissions but reduces methane emissions if it is naturally occurring waste.
Forest-based biomass has recently come under fire (ahem) from a number of environmental organizations, including Greenpeace and the Natural Resources Defense Council, for the harmful impacts it can have on forests and the climate. Because any part of the tree can be burned, the harvesting of trees for energy production encourages Whole-Tree Harvesting, which removes more nutrients and soil cover than regular harvesting, and can be harmful to the long-term health of the forest. In some jurisdictions, forest biomass is increasingly consisting of elements essential to functioning forest ecosystems, including standing trees, naturally disturbed forests and remains of traditional logging operations that were previously left in the forest.

So if even renewables are not entirely green, how do we reconcile the need to find enough new power to combat the fall in reserves of ‘traditional’ sources, with the desire to find environmentally-friendly solutions? The answer is probably in how we manage the balance in the pie chart above. Despite heavy investment into renewables by many world economies, most have now accepted that nuclear is going to have to increase as fossil fuels decline. Again this is a controversial topic, and whilst nuclear is seen by some as a ‘cleaner’ if not ‘greener’ source, many people understandably have concerns about the disposal of the waste.
It is easy to see why the terms ‘renewable’ and ‘green’ are used interchangeably, although whilst we are able to define ‘renewable’ quite clearly, nobody has yet come up with a satisfactory explanation of how to define ‘green’. It is most commonly viewed as energy supplied by companies such as ‘Good’ energy who market themselves as ‘100% renewable’ alongside the aim of reducing CO2 emissions. But what is considered to be a green tariff also varies considerably from company to company. Some green tariffs for example work by making a contribution to environmental schemes, but don’t necessarily guarantee the energy you are supplied with comes directly from renewable sources. In an attempt to combat the wide variation, in 2010 Ofgem launched a green energy certification scheme which allows energy suppliers to have their tariffs independently audited and declared officially green if they meet certain requirements. Energy suppliers must adhere to one of these three additional environmental benefits to be certified:
• Donate money to charities or trust funds that invest in renewable projects.
• Support or deliver schemes that have energy efficiency benefits, such as installing loft insulation.
• Contribute to carbon offsetting.

Again, nothing to say that they are supplying you with renewable energy. In fact, some of what I would consider to be the greenest tariffs, as seen through my own prism, don’t qualify for the OFGEM green Energy Certification. So buyer beware, if you really do want to be ‘green’ then best you come up with your own definition of green and then seek out the company that most closely mirrors your own definition. Relying on corporate marketing or official certification is not advised by itself; you are going to need to do a bit of research and legwork to ease your environmental conscience.